The present invention relates generally to fiber optics, and, more specifically, to a video display panel.
The present invention is an improvement over U.S. Pat. Nos. 5,381,502 and 5,625,736 by the same inventor.
These patents disclose optical display panels including laminated waveguides defining a wedge having a narrow inlet face along the bottom thereof, and a vertical outlet screen disposed obliquely thereto. The waveguides are inclined at a small acute angle between the inlet face and the screen for transmitting image light with total internal reflection.
The optical panel is extremely thin in depth compared to its height and width and requires suitable projection optics to distribute the image light across the small inlet face for expansion at the screen. The waveguides are preferably ribbons extending the full width of the panel, and are stacked vertically together along the height of the panel for effecting a suitable vertical resolution in the screen corresponding with the same number of stacked waveguides. Horizontal resolution is effected by horizontal modulation of the image light across the inlet face.
In this wedge construction, the waveguides have varying length, with the shortest being at the bottom of the screen and the longest being at the top of the screen. In this way, the individual inlets ends of the several waveguides may be disposed in a common plane at the bottom of the screen to define the narrow inlet face.
Correspondingly, the projector used for spreading the image light across the inlet face requires a suitable lens system or image optics having different focal planes across the width and height of the screen. Furthermore, since the efficiency of light transmission through the waveguides is not perfect, losses in light intensity increase with waveguide length from the bottom to the top of the screen. Such losses may be minimized by using higher quality waveguides, with an attendant increase in cost.
Although the wedge optical display may be made relatively thin, it may be made relatively large in width and height with a corresponding weight. And, the variable length waveguides increase manufacturing complexity and cost, and require a relatively complex and expensive light projector with different focal planes for horizontal and vertical focusing of the image.
Accordingly, it is desired to further reduce the thickness and complexity of an optical panel for reducing weight and cost with enhanced performance.